Sildenafil, N-desmethyl-sildenafil and Zaprinast enhance photoreceptor response in the isolated rat retina

  • Neurochem Int. 2003 Nov;43(6):591-5. doi: 10.1016/s0197-0186(03)00045-7.
Péter Barabás  1 ,  Zsuzsanna Riedl ,  Julianna Kardos
Affiliations
  • 1. Department of Neurochemistry, Institute of Chemistry, Chemical Research Center, Hungarian Academy of Sciences, Pusztaszeri út 59-67, H 1025, Budapest, Hungary.
PMID: 12820988 DOI: 10.1016/s0197-0186(03)00045-7
Abstract

Here we report that the active component of Viagra, Sildenafil and the first metabolite, N-desmethyl-sildenafil (UK-103, 320) increased the amplitude of flash-evoked electroretinogram (ERG) of dark-adapted albino rat retina. Effects of Sildenafil and N-desmethyl-sildenafil were comparable to those of the known phosphodiesterase inhibitor, Zaprinast. The photoreceptor cell response was isolated by blocking the glial K(+) ion-buffering and the on-bipolar components of the ERG with the use of BaCl(2) (500 microM) and the specific type VI metabotropic glutamate receptor agonist, DL-2-amino-4-phosphonobutyric acid (25 microM), respectively. Zaprinast, Sildenafil and N-desmethyl-sildenafil (1 microM each) increased the amplitude of photoreceptor cell response either. Besides, Sildenafil was significantly more effective than N-desmethyl-sildenafil. These findings suggest an increased sensitivity of photoreceptor cells in the presence of Sildenafil and it is metabolite.

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